If you want to trigger an event before the document is loaded, use the onbeforeunload event.
You can try running the following code to learn how to implement the onbeforeunload event in JavaScript.
<!DOCTYPE html>
<html>
<body onbeforeunload="return myFunction()">
<a href="https://www.qries.com">Click to open Qries</a>
<script>
function myFunction() {
return "Working with onbeforeunload event";
}
</script>
</body>
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